1. Field of the Invention
The present invention relates to a sheet loading device, and a sheet conveying device that includes the sheet loading device, and an image forming apparatus.
2. Description of the Related Art
In an image forming apparatus such as a copier, a printer, a facsimile, or a multifunction product (MFP) of the copier, the printer, and the facsimile, generally a sheet, which is housed in a sheet cassette, is transmitted by a sheet feeder to a transport path side, an image forming unit forms an image on the sheet that is transported via the transport path, and the sheet is transmitted to a sheet ejection tray.
The sheet feeder includes a feeding roller that transmits the sheet. The feeding roller and a separating pad, which is arranged opposite the feeding roller, separate each single sheet and transmit the sheet.
In a sheet feeding structure mentioned earlier, during transmission of the sheet, the sheet causes a stickslip on the separating pad. The stickslip indicates a precise operation in which the sheet on the separating pad is repeatedly stopped and transported for a moment. Minute oscillations, which occur due to the stickslip, are transmitted to a sheet cassette and peripheral members of the sheet cassette, thus causing abnormal noise. Due to this, environmental amenity worsens.
Following technologies are suggested as means to overcome the drawback mentioned earlier. In a technology disclosed in Japanese Patent Application Laid-open No. 2005-193526, a spindle is attached to a holder of the feeding roller such that the spindle minutely oscillates. The spindle is caused to oscillate at a phase that differs from a phase of the feeding roller, thus reducing the oscillations of the feeding roller. Further, in another technology disclosed in Japanese Patent Application Laid-open No. 2005-170520, an oscillation absorbing material formed of rubber is arranged between a sheet loading plate and a spring that presses the sheet loading plate in an upward direction.
However, in the technology disclosed in Japanese Patent Application Laid-open No. 2005-193526, presence of the spindle affects a mutual suppress strength between the feeding roller and the separating pad. Due to this, the feeding roller and the separating pad are not able to exhibit a stable sheet feeding ability. Further, even in the technology disclosed in Japanese Patent Application Laid-open No. 2005-170520, inclusion of the oscillation absorbing material affects the mutual suppress strength between the sheet loading plate and the feeding roller, thus hampering a stable sheet feeding.